An important problem facing the country is the increased demand for electrical power. For the most part, electrical utilities have relied on volunteer cooperation from individuals and industry to reduce power consumption. However, with the capacities of power generating facilities being more frequently strained to the point of causing occasional "brown-outs," substantial attention has been given to ways of reducing electrical demand.
Electrical rates based on peak demand are common in industry. If the peak demand can be reduced by diverting some energy requirements to non-peak hours, a considerable savings on electrical bills can be realized. There have been a number of proposals to also place households on peak demand rates. This would give the home owner an incentive to control his power consumption provided he is supplied with a device which will indicate to him when a peak demand period is being experienced.
Another possibility for reducing peak demand period consumption is to remotely control the operation of energy consuming devices both in industry and in the home.
With either of the foregoing approaches, it is necessary to provide a communication system between the utility which monitors the total power consumption and the customers. Several attempts have been made in the past to accomplish this. Such efforts are summarized in an article entitled "Creative Electric Load Management" by Thomas Laaspere and Alvin O. Converse, appearing in the February, 1975 issue of IEEE SPECTRUM, pp. 46-50. Basically, these previous approaches have
a. used the transmission and distribution lines as the transmission medium; or
b. employed only radio communication.
With respect to transmission line systems, the use of low frequency signals on the lines requires a great amount of power to successfully transmit. When higher frequency carriers are employed, substantial transmission line losses are experienced.
With a radio system, a separate receiver is required at each remote location, and this is an extremely expensive undertaking. Furthermore, reception tends to be unreliable since the receivers are often located in low lying areas, near reflectors, etc.